Background:The accurate identification of cardiac abnormalities is essential for proper diagnosis and effective treatment of cardiovascular diseases.Method:This work introduces an advanced methodology for detecting ca...Background:The accurate identification of cardiac abnormalities is essential for proper diagnosis and effective treatment of cardiovascular diseases.Method:This work introduces an advanced methodology for detecting cardiac abnormalities and estimating electrocardiographic age(ECG Age)using sophisticated signal processing and deep learning techniques.This study looks at six main heart conditions found in 12-lead electrocardiogram(ECG)data.It addresses important issues like class imbalances,missing lead scenarios,and model generalizations.A modified residual neural network(ResNet)architecture was developed to enhance the detection of cardiac abnormalities.Results:The proposed ResNet demonst rated superior performance when compared with two linear models and an alternative ResNet architectures,achieving an overall classification accuracy of 91.25%and an F1 score of 93.9%,surpassing baseline models.A comprehensive lead loss analysis was conducted,evaluating model performance across 4096 combinations of missing leads.The results revealed that pulse rate-based factors remained robust with up to 75%lead loss,while block-based factors experienced significant performance declines beyond the loss of four leads.Conclusion:This analysis highlighted the importance of addressing lead loss impacts to maintain a robust model.To optimize performance,targeted training approaches were developed for different conditions.Based on these insights,a grouping strategy was implemented to train specialized models for pulse rate-based and block-based conditions.This approach resulted in notable improvements,achieving an overall classification accuracy of 95.12%and an F1 score of 95.79%.展开更多
In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But...In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But they still face challenges in terms of computational requirements,overfitting and generalization issues,etc.To resolve such issues,optimization algorithms provide greater control and transparency in designing digital filters for image enhancement and denoising.Therefore,this paper presented a novel denoising approach for medical applications using an Optimized Learning⁃based Multi⁃level discrete Wavelet Cascaded Convolutional Neural Network(OLMWCNN).In this approach,the optimal filter parameters are identified to preserve the image quality after denoising.The performance and efficiency of the OLMWCNN filter are evaluated,demonstrating significant progress in denoising medical images while overcoming the limitations of conventional methods.展开更多
Urban air quality degradation from rising CO_(2) is acute in rapidly developing tropical cities such as Makassar,Indonesia.We deploy a drone-based Internet of Things(IoT)platform for real-time CO_(2) monitoring,integr...Urban air quality degradation from rising CO_(2) is acute in rapidly developing tropical cities such as Makassar,Indonesia.We deploy a drone-based Internet of Things(IoT)platform for real-time CO_(2) monitoring,integrating low-cost sensors(NDIR,MQ135,MG811)on a DJI Phantom 4 with cloud streaming to Firebase.Measurements were collected at five sites,namely Jl.AP.Pettarani,Jl.Ahmad Yani,Jl.Sultan Hasanuddin,Jl.Nusantara,and KIMA at 08:00,12:00,and 16:00 in September 2024 while vertically profiling 1-20 m with three repeat flights per site and time.Descriptive statistics and one-way ANOVA with Tukey HSD assessed spatio-temporal differences;Pearson correlation quantified cross-sensor agreement.Results show marked spatial and diurnal variability:Jl.AP.Pettarani exhibits the highest mean concentration(442.5 ppm),likely due to flyover-induced trapping,whereas Jl.Ahmad Yani records the lowest(390.0 ppm).Vertical profiles reveal mid-altitude peaks in street-canyon and industrial settings,and dilution with height in greener areas,indicating ventilation contrasts.Preprocessing removed outliers and applied temperature-humidity corrections to low-cost sensors.Differences across locations and times are statistically significant(p<0.05),and cross-sensor correlations are strong(r≈0.88-0.96)after correction.Compared with fixed ground stations,the system provides fine-scale three-dimensional coverage and real-time visualization useful for field decisions.Limitations include payload-constrained endurance and intermittent data loss in obstructed areas.Findings support targeted interventions,improving canyon ventilation around flyovers and expanding urban greenery relevant to Makassar and similar tropical cities.展开更多
C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under t...C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions.Structural,morphologic and electrical properties of ZnO films are characterized by X-ray diffraction(XRD),high-resistance instrument,energy dispersive X-ray spectroscopy(EDS) and scanning electronic microscopy(SEM).As the O2/(O2+Ar) ratio increasing from 1/12 to 5/12,the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly.After annealing,the ZnO films deposited in O2/(O2+Ar) =1/12 and 3/12 are improved greatly in crystallinity,and their electrical resistivity is enhanced by two orders of magnitude,while those deposited in O2/(O2+Ar) =5/12 are scarcely changed in crystallinity,and their resistivity is only increased by one order.In addition,the ZnO films deposited in O2/(O2+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.展开更多
A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)s...A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)signals by setting frequencies at f GHz,f/2 GHz and f/4 GHz.Here,the first stage acts as subcarrier generator,the second stage acts as subcarrier doubler,and the third stage acts as subcarrier quadrupler.In addition,a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal.In this paper,cascading three stages of EAMs driven by50 GHz,25 GHz and 12.5 GHz clock sources,we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 d B.Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated.Principal analysis and simulation of this technique are demonstrated.展开更多
This study presents a parametric system identification approach to estimate the dynamics of a chemical plant from experimental data and develops a robust PID controller for the plant.Parametric system identification o...This study presents a parametric system identification approach to estimate the dynamics of a chemical plant from experimental data and develops a robust PID controller for the plant.Parametric system identification of the heat exchanger system has been carried out using experimental data and prediction error method.The estimated model of the heat exchanger system is a time-delay model and a robust PID controller for the time-delayed model has been designed considering weighted sensitivity criteria.The mathematical background of parametric system identification,stability analysis,and H∞ weighted sensitivity analysis have been provided in this paper.A graphical plot has been provided to determine the stability region in the(Kp,Ki),(Kp,Kd)and(KuKd)plane.The stability region is a locus dependent on parameters of the controller and frequency,in the parameter plane.展开更多
Self-lubricating A1203-15wt% ZrO2 composites with sulfides, such as molybdenum disulfide （MoS2） and tungsten disulfide （WSz） serving as solid lubricants, were fabricated by using the pulse electric current sinteri...Self-lubricating A1203-15wt% ZrO2 composites with sulfides, such as molybdenum disulfide （MoS2） and tungsten disulfide （WSz） serving as solid lubricants, were fabricated by using the pulse electric current sintering （PECS） technique. The coefficient of friction （COF） of the A1203-15wt% ZrO2 composite without/with sulfides was in the range of 0.37-0.48 and 0.27-0.49, respectively. As the amoant of sul- fides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.展开更多
The fast growing demands and increasing awareness for the environment, PV systems are being rapidly installed for numerous applications.However, one of the important challenges in utilizing a PV source is the maximum ...The fast growing demands and increasing awareness for the environment, PV systems are being rapidly installed for numerous applications.However, one of the important challenges in utilizing a PV source is the maximum power harnessing using various maximum power point tracking techniques available. With the large number of MPPT techniques, each having some merits and demerits, confusion is always there for their proper selection. Discussion on various proposed procedures for maximum power point tracking of photovoltaic array has been done. Based on different parameters analysis of MPPT techniques is carried out. This assessment will serve as a suitable reference for selection, understanding different ways and means of MPPT.展开更多
Simple models are proposed for the calculation of refractive index n and electronic polarizability α of AⅠBⅢC2Ⅵ and AⅡBⅣC2Ⅴ compounds of groups of chalcopyrite semiconductors from their energy gap data. The val...Simple models are proposed for the calculation of refractive index n and electronic polarizability α of AⅠBⅢC2Ⅵ and AⅡBⅣC2Ⅴ compounds of groups of chalcopyrite semiconductors from their energy gap data. The values family and 12 compounds of AⅡBⅣC2Ⅴ family are calculated for the work. The proposed models are applicable for the whole range of energy gap materials. The calculated values are compared with the available experimental and reported values. A fairly good agreement between them is obtained.展开更多
The effects of annealing temperature on the sol–gel-derived ZnO thin films deposited on n-Sh100 i substrates by sol–gel spin coating method have been studied in this paper.The structural,optical,and electrical prope...The effects of annealing temperature on the sol–gel-derived ZnO thin films deposited on n-Sh100 i substrates by sol–gel spin coating method have been studied in this paper.The structural,optical,and electrical properties of ZnO thin films annealed at 450,550,and 650 °C in the Ar gas atmosphere have been investigated in a systematic way.The XRD analysis shows a polycrystalline nature of the films at all three annealing temperatures.Further,the crystallite size is observed to be increased with the annealing temperature,whereas the positions of various peaks in the XRD spectra are found to be red-shifted with the temperature.The surface morphology studied through the scanning electron microscopy measurements shows a uniform distribution of ZnO nanoparticles over the entire Si substrates of enhanced grain sizes with the annealing temperature.Optical properties investigated by photoluminescence spectroscopy shows an optical band gap varying in the range of 3.28–3.15 eV as annealing temperature is increased from 450 to 650 °C,respectively.The fourpoint probe measurement shows a decrease in resistivity from 2：1 10 2to 8：1 10 4X cm with the increased temperature from 450 to 650 °C.The study could be useful for studying the sol–gel-derived ZnO thin film-based devices for various electronic,optoelectronic,and gas sensing applications.展开更多
Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler s...Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler spectrum, the low signal to clutter ratio （SCR） environment degrades the performance of signal process- ing algorithms. This paper addresses this challenging problem by using an S2-method and an adaptive clutter rejection scheme. The proposed S2-method improves the S-method by eliminating inter- ference between signals, and thus it enables multi-target signals to be reconstructed individually. The proposed adaptive clutter rejec- tion scheme is based on an adaptive notch filter, which is designed according to the envelop of the clutter spectrum. Experiments with simulated targets added into radar sea clutter echo and real air target data illustrate the effectiveness of the proposed method.展开更多
We examine theoretically the performance of an Hg0.77Cd0.23Te based p-n photodetector/HFET optical receiver due to its possible application at 10.6 μm free space optical communication system at high bit rate.A rigoro...We examine theoretically the performance of an Hg0.77Cd0.23Te based p-n photodetector/HFET optical receiver due to its possible application at 10.6 μm free space optical communication system at high bit rate.A rigorous noise model of the receiver has been developed for this purpose.We calculate the total noise and sensitivity of the receiver.The front-end of the receiver exhibits a sensitivity of -45 dBm at a bit rate of 1 Gb/s and -30 dBm at a bit rate of 10 Gb/s,and the total mean-square noise curren t〈i2n〉=5×10-15 A2 at a bit rate of 1 Gb/s an d〈i2n〉 =10-12 A2 at a bit rate of 10 Gb/s,and a 3-dB bandwidth of 10 GHz.展开更多
With the explosive advancements in wireless communications and digital electronics,some tiny devices,sensors,became a part of our daily life in numerous elds.Wireless sensor networks(WSNs)is composed of tiny sensor de...With the explosive advancements in wireless communications and digital electronics,some tiny devices,sensors,became a part of our daily life in numerous elds.Wireless sensor networks(WSNs)is composed of tiny sensor devices.WSNs have emerged as a key technology enabling the realization of the Internet of Things(IoT).In particular,the sensor-based revolution of WSN-based IoT has led to considerable technological growth in nearly all circles of our life such as smart cities,smart homes,smart healthcare,security applications,environmental monitoring,etc.However,the limitations of energy,communication range,and computational resources are bottlenecks to the widespread applications of this technology.In order to tackle these issues,in this paper,we propose an Energy-efcient Transmission Range Optimized Model for IoT(ETROMI),which can optimize the transmission range of the sensor nodes to curb the hot-spot problem occurring in multi-hop communication.In particular,we maximize the transmission range by employing linear programming to alleviate the sensor nodes’energy consumption and considerably enhance the network longevity compared to that achievable using state-of-the-art algorithms.Through extensive simulation results,we demonstrate the superiority of the proposed model.ETROMI is expected to be extensively used for various smart city,smart home,and smart healthcare applications in which the transmission range of the sensor nodes is a key concern.展开更多
The effect of In composition on two-dimensional electron gas in wurtzite AlGaN/InGaN heterostructures is theoretically investigated. The sheet carrier density is shown to increase nearly linearly with In mole fraction...The effect of In composition on two-dimensional electron gas in wurtzite AlGaN/InGaN heterostructures is theoretically investigated. The sheet carrier density is shown to increase nearly linearly with In mole fraction x, due to the increase in the polarization charge at the AlGaN/InGaN interface. The electron sheet density is enhanced with the doping in the AlGaN layer. The sheet carrier density is as high as 3.7×1013 cm^-2 at the donor density of 10×1018 cm^-3 for the HEMT structure with x=0.3. The contribution of additional donor density on the electron sheet density is nearly independent of the In mole fraction.展开更多
Tool wear state classification has good potential to play a critical role in ensuring the dimensional accuracy of the work piece and prevention of damage to cutting tool in machining process. During machining process,...Tool wear state classification has good potential to play a critical role in ensuring the dimensional accuracy of the work piece and prevention of damage to cutting tool in machining process. During machining process, tool wear is an important factor which contributes to the variation of spindle motor current, speed, feed and depth of cut. In the present work, online tool wear state detecting method with spindle motor current in turning operation for Al/SiC composite material is presented. By analyzing the effects of tool wear as well as the cutting parameters on the current signal, the models on the relationship between the current signals and the cutting parameters are established with partial design taken from experimental data and regression analysis. The fuzzy classification method is used to classify the tool wear states so as to facilitate defective tool replacement at the proper time.展开更多
This paper presents an energy efficient architecture for successive approximation register(SAR)analog to digital converter(ADC).SAR ADCs with a capacitor array structure have been widely used because of its simple arc...This paper presents an energy efficient architecture for successive approximation register(SAR)analog to digital converter(ADC).SAR ADCs with a capacitor array structure have been widely used because of its simple architecture and relatively high speed.However,conventional SAR ADCs consume relatively high energy due to the large number of capacitors used in the capacitor array and their sizes scaled up along with the number of bits.The proposed architecture reduces the energy consumption as well as the capacitor size by employing a new array architecture that scales down the reference voltages instead of scaling up the capacitor sizes.The proposed 12-bit SAR ADC is implemented in Complementary Metal Oxide Semiconductor(CMOS)0.13 um library using Cadence Virtuoso design tool.Simulation results and mathematical model demonstrate the overall energy savings of up to 97.3%compared with conventional SAR ADC,67%compared with the SAR ADC with split capacitor,and 35%compared with the resistor and capacitor(R&C)Hybrid SAR ADC.The ADC achieves an effective number of bits(ENOB)of 11.27 bits and consumes 61.7 uW at sampling rate of 2.56 MS/s,offering an energy consumption of 9.8 fJ per conversion step.The proposed SAR ADC offers 95.5%reduction in chip core area compared to conventional architecture,while occupying an active area of 0.088 mm2.展开更多
In this paper,we report the design and simulation of a bias-selectable dual-band photodetector operating in the visible(VIS)and near infrared(NIR)regions.The photodetector consists of two back-to-back avalanche photod...In this paper,we report the design and simulation of a bias-selectable dual-band photodetector operating in the visible(VIS)and near infrared(NIR)regions.The photodetector consists of two back-to-back avalanche photodiodes(APDs)with InGaAs and Si absorption layers respectively.The structure and electrical and optical properties of the dual-color photodetector were designed and simulated by exploiting Silvaco software.The results obtained on the basis of numerical simulation include the current-voltage,capacitance-voltage,spectral response,etc.The optical simulation shows the detection capability in the VIS and NIR ranges,cut-off wavelengths of 1.0μm and 1.8μm depending on the applied bias polarity.Comparing with using the PIN structure as element device,the dual-band photodetector based on the APD configuration could detect the very weak signal,realizing few photons,even single photon detection.展开更多
To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a syn...To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.展开更多
Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles(mNPs) on the surfaces of catalytic metal oxide supports is challenging.This can be attributed to the hetero...Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles(mNPs) on the surfaces of catalytic metal oxide supports is challenging.This can be attributed to the heterogeneity and large size at the nanoscale,the poorly defined catalyst nanostructure,and thermodynamic immiscibility of the strongly repelling metallic elements.To address these challenges,an ultrasonic-assisted coincident electro-oxidation-reduction-precipitation(U-SEO-P) is presented to fabricate ultra-stable PtRuAgCoCuP NPs,which produces numerous active intermediates and induces strong metal-support interactions.To sort the active high-entropy mNPs,individual NPs are described on the support surface and the role of deep learning in understanding/predicting the features of PtRuAgCoCu@TiO_(x) catalysts is explained.Notably,this deep learning approach required minimal to no human input.The as-prepared PtRuAgCoCu@TiO_(x) catalysts can be used to catalyze various important chemical reactions,such as a high reduction conversion(100% in 30 s),with no loss of catalytic activity even after 20 cycles of nitroarene and ketone/aldehyde,which is several times higher than commercial Pt@TiO_(x) owing to individual PtRuAgCoCuP NPs on TiO_(x) surface.In this study,we present the "Totally Defined Catalysis" concept,which has enormous potential for the advancement of high-activity catalysts in the reduction of organic compounds.展开更多
A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（...A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（θ;μ;κ） is a two-mode rotational displacing-squeezing operator in the 〈η｜ representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac＇s representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.展开更多
文摘Background:The accurate identification of cardiac abnormalities is essential for proper diagnosis and effective treatment of cardiovascular diseases.Method:This work introduces an advanced methodology for detecting cardiac abnormalities and estimating electrocardiographic age(ECG Age)using sophisticated signal processing and deep learning techniques.This study looks at six main heart conditions found in 12-lead electrocardiogram(ECG)data.It addresses important issues like class imbalances,missing lead scenarios,and model generalizations.A modified residual neural network(ResNet)architecture was developed to enhance the detection of cardiac abnormalities.Results:The proposed ResNet demonst rated superior performance when compared with two linear models and an alternative ResNet architectures,achieving an overall classification accuracy of 91.25%and an F1 score of 93.9%,surpassing baseline models.A comprehensive lead loss analysis was conducted,evaluating model performance across 4096 combinations of missing leads.The results revealed that pulse rate-based factors remained robust with up to 75%lead loss,while block-based factors experienced significant performance declines beyond the loss of four leads.Conclusion:This analysis highlighted the importance of addressing lead loss impacts to maintain a robust model.To optimize performance,targeted training approaches were developed for different conditions.Based on these insights,a grouping strategy was implemented to train specialized models for pulse rate-based and block-based conditions.This approach resulted in notable improvements,achieving an overall classification accuracy of 95.12%and an F1 score of 95.79%.
文摘In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But they still face challenges in terms of computational requirements,overfitting and generalization issues,etc.To resolve such issues,optimization algorithms provide greater control and transparency in designing digital filters for image enhancement and denoising.Therefore,this paper presented a novel denoising approach for medical applications using an Optimized Learning⁃based Multi⁃level discrete Wavelet Cascaded Convolutional Neural Network(OLMWCNN).In this approach,the optimal filter parameters are identified to preserve the image quality after denoising.The performance and efficiency of the OLMWCNN filter are evaluated,demonstrating significant progress in denoising medical images while overcoming the limitations of conventional methods.
基金supported by the Directorate of Research,Technology,and Community Service(DRTPM),Ministry of Education,Culture,Research,and Technology,grant number 2817/UN36.11/LP2M/2024.
文摘Urban air quality degradation from rising CO_(2) is acute in rapidly developing tropical cities such as Makassar,Indonesia.We deploy a drone-based Internet of Things(IoT)platform for real-time CO_(2) monitoring,integrating low-cost sensors(NDIR,MQ135,MG811)on a DJI Phantom 4 with cloud streaming to Firebase.Measurements were collected at five sites,namely Jl.AP.Pettarani,Jl.Ahmad Yani,Jl.Sultan Hasanuddin,Jl.Nusantara,and KIMA at 08:00,12:00,and 16:00 in September 2024 while vertically profiling 1-20 m with three repeat flights per site and time.Descriptive statistics and one-way ANOVA with Tukey HSD assessed spatio-temporal differences;Pearson correlation quantified cross-sensor agreement.Results show marked spatial and diurnal variability:Jl.AP.Pettarani exhibits the highest mean concentration(442.5 ppm),likely due to flyover-induced trapping,whereas Jl.Ahmad Yani records the lowest(390.0 ppm).Vertical profiles reveal mid-altitude peaks in street-canyon and industrial settings,and dilution with height in greener areas,indicating ventilation contrasts.Preprocessing removed outliers and applied temperature-humidity corrections to low-cost sensors.Differences across locations and times are statistically significant(p<0.05),and cross-sensor correlations are strong(r≈0.88-0.96)after correction.Compared with fixed ground stations,the system provides fine-scale three-dimensional coverage and real-time visualization useful for field decisions.Limitations include payload-constrained endurance and intermittent data loss in obstructed areas.Findings support targeted interventions,improving canyon ventilation around flyovers and expanding urban greenery relevant to Makassar and similar tropical cities.
基金supported by the National Natural Science Foundation of China (No. 50972105)Tianjin Natural Science Foundation (No.09JCZDJC16500)
文摘C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions.Structural,morphologic and electrical properties of ZnO films are characterized by X-ray diffraction(XRD),high-resistance instrument,energy dispersive X-ray spectroscopy(EDS) and scanning electronic microscopy(SEM).As the O2/(O2+Ar) ratio increasing from 1/12 to 5/12,the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly.After annealing,the ZnO films deposited in O2/(O2+Ar) =1/12 and 3/12 are improved greatly in crystallinity,and their electrical resistivity is enhanced by two orders of magnitude,while those deposited in O2/(O2+Ar) =5/12 are scarcely changed in crystallinity,and their resistivity is only increased by one order.In addition,the ZnO films deposited in O2/(O2+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.
文摘A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)signals by setting frequencies at f GHz,f/2 GHz and f/4 GHz.Here,the first stage acts as subcarrier generator,the second stage acts as subcarrier doubler,and the third stage acts as subcarrier quadrupler.In addition,a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal.In this paper,cascading three stages of EAMs driven by50 GHz,25 GHz and 12.5 GHz clock sources,we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 d B.Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated.Principal analysis and simulation of this technique are demonstrated.
文摘This study presents a parametric system identification approach to estimate the dynamics of a chemical plant from experimental data and develops a robust PID controller for the plant.Parametric system identification of the heat exchanger system has been carried out using experimental data and prediction error method.The estimated model of the heat exchanger system is a time-delay model and a robust PID controller for the time-delayed model has been designed considering weighted sensitivity criteria.The mathematical background of parametric system identification,stability analysis,and H∞ weighted sensitivity analysis have been provided in this paper.A graphical plot has been provided to determine the stability region in the(Kp,Ki),(Kp,Kd)and(KuKd)plane.The stability region is a locus dependent on parameters of the controller and frequency,in the parameter plane.
基金financially supported by the Korea Foundation for International Cooperation of Science and Technology(KICOS 2008-0143)the Global Research Laboratory(GRL)Program of the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science,and Technology(MEST)of Korea(No.2010-00339)
文摘Self-lubricating A1203-15wt% ZrO2 composites with sulfides, such as molybdenum disulfide （MoS2） and tungsten disulfide （WSz） serving as solid lubricants, were fabricated by using the pulse electric current sintering （PECS） technique. The coefficient of friction （COF） of the A1203-15wt% ZrO2 composite without/with sulfides was in the range of 0.37-0.48 and 0.27-0.49, respectively. As the amoant of sul- fides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.
文摘The fast growing demands and increasing awareness for the environment, PV systems are being rapidly installed for numerous applications.However, one of the important challenges in utilizing a PV source is the maximum power harnessing using various maximum power point tracking techniques available. With the large number of MPPT techniques, each having some merits and demerits, confusion is always there for their proper selection. Discussion on various proposed procedures for maximum power point tracking of photovoltaic array has been done. Based on different parameters analysis of MPPT techniques is carried out. This assessment will serve as a suitable reference for selection, understanding different ways and means of MPPT.
文摘Simple models are proposed for the calculation of refractive index n and electronic polarizability α of AⅠBⅢC2Ⅵ and AⅡBⅣC2Ⅴ compounds of groups of chalcopyrite semiconductors from their energy gap data. The values family and 12 compounds of AⅡBⅣC2Ⅴ family are calculated for the work. The proposed models are applicable for the whole range of energy gap materials. The calculated values are compared with the available experimental and reported values. A fairly good agreement between them is obtained.
文摘The effects of annealing temperature on the sol–gel-derived ZnO thin films deposited on n-Sh100 i substrates by sol–gel spin coating method have been studied in this paper.The structural,optical,and electrical properties of ZnO thin films annealed at 450,550,and 650 °C in the Ar gas atmosphere have been investigated in a systematic way.The XRD analysis shows a polycrystalline nature of the films at all three annealing temperatures.Further,the crystallite size is observed to be increased with the annealing temperature,whereas the positions of various peaks in the XRD spectra are found to be red-shifted with the temperature.The surface morphology studied through the scanning electron microscopy measurements shows a uniform distribution of ZnO nanoparticles over the entire Si substrates of enhanced grain sizes with the annealing temperature.Optical properties investigated by photoluminescence spectroscopy shows an optical band gap varying in the range of 3.28–3.15 eV as annealing temperature is increased from 450 to 650 °C,respectively.The fourpoint probe measurement shows a decrease in resistivity from 2：1 10 2to 8：1 10 4X cm with the increased temperature from 450 to 650 °C.The study could be useful for studying the sol–gel-derived ZnO thin film-based devices for various electronic,optoelectronic,and gas sensing applications.
基金supported by the State Key Program of National Natural Science Foundation of China(61032011)
文摘Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler spectrum, the low signal to clutter ratio （SCR） environment degrades the performance of signal process- ing algorithms. This paper addresses this challenging problem by using an S2-method and an adaptive clutter rejection scheme. The proposed S2-method improves the S-method by eliminating inter- ference between signals, and thus it enables multi-target signals to be reconstructed individually. The proposed adaptive clutter rejec- tion scheme is based on an adaptive notch filter, which is designed according to the envelop of the clutter spectrum. Experiments with simulated targets added into radar sea clutter echo and real air target data illustrate the effectiveness of the proposed method.
文摘We examine theoretically the performance of an Hg0.77Cd0.23Te based p-n photodetector/HFET optical receiver due to its possible application at 10.6 μm free space optical communication system at high bit rate.A rigorous noise model of the receiver has been developed for this purpose.We calculate the total noise and sensitivity of the receiver.The front-end of the receiver exhibits a sensitivity of -45 dBm at a bit rate of 1 Gb/s and -30 dBm at a bit rate of 10 Gb/s,and the total mean-square noise curren t〈i2n〉=5×10-15 A2 at a bit rate of 1 Gb/s an d〈i2n〉 =10-12 A2 at a bit rate of 10 Gb/s,and a 3-dB bandwidth of 10 GHz.
基金supported by Korea Electric Power Corporation(Grant Number:R18XA02)。
文摘With the explosive advancements in wireless communications and digital electronics,some tiny devices,sensors,became a part of our daily life in numerous elds.Wireless sensor networks(WSNs)is composed of tiny sensor devices.WSNs have emerged as a key technology enabling the realization of the Internet of Things(IoT).In particular,the sensor-based revolution of WSN-based IoT has led to considerable technological growth in nearly all circles of our life such as smart cities,smart homes,smart healthcare,security applications,environmental monitoring,etc.However,the limitations of energy,communication range,and computational resources are bottlenecks to the widespread applications of this technology.In order to tackle these issues,in this paper,we propose an Energy-efcient Transmission Range Optimized Model for IoT(ETROMI),which can optimize the transmission range of the sensor nodes to curb the hot-spot problem occurring in multi-hop communication.In particular,we maximize the transmission range by employing linear programming to alleviate the sensor nodes’energy consumption and considerably enhance the network longevity compared to that achievable using state-of-the-art algorithms.Through extensive simulation results,we demonstrate the superiority of the proposed model.ETROMI is expected to be extensively used for various smart city,smart home,and smart healthcare applications in which the transmission range of the sensor nodes is a key concern.
文摘The effect of In composition on two-dimensional electron gas in wurtzite AlGaN/InGaN heterostructures is theoretically investigated. The sheet carrier density is shown to increase nearly linearly with In mole fraction x, due to the increase in the polarization charge at the AlGaN/InGaN interface. The electron sheet density is enhanced with the doping in the AlGaN layer. The sheet carrier density is as high as 3.7×1013 cm^-2 at the donor density of 10×1018 cm^-3 for the HEMT structure with x=0.3. The contribution of additional donor density on the electron sheet density is nearly independent of the In mole fraction.
文摘Tool wear state classification has good potential to play a critical role in ensuring the dimensional accuracy of the work piece and prevention of damage to cutting tool in machining process. During machining process, tool wear is an important factor which contributes to the variation of spindle motor current, speed, feed and depth of cut. In the present work, online tool wear state detecting method with spindle motor current in turning operation for Al/SiC composite material is presented. By analyzing the effects of tool wear as well as the cutting parameters on the current signal, the models on the relationship between the current signals and the cutting parameters are established with partial design taken from experimental data and regression analysis. The fuzzy classification method is used to classify the tool wear states so as to facilitate defective tool replacement at the proper time.
基金supported by Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(No.2020-0-01304,Development of Self-learnable Mobile Recursive Neural Network Processor Technology)also supported by the MSIT(Ministry of Science and ICT),Korea,under the Grand Information Technology Research Center support program(IITP-2020-0-01462)+3 种基金supervised by the IITP(Institute for Information&communications Technology Planning&Evaluation)”And also financially supported by the Ministry of Small and Medium-sized Enterprises(SMEs)and Startups(MSS),Korea,under the“Regional Specialized Industry Development Plus Program(R&D,S3091644)”supervised by the Korea Institute for Advancement of Technology(KIAT)supported by the AURI(Korea Association of University,Research institute and Industry)grant funded by the Korea Government(MSS:Ministry of SMEs and Startups).(No.S2929950,HRD program for 2020).
文摘This paper presents an energy efficient architecture for successive approximation register(SAR)analog to digital converter(ADC).SAR ADCs with a capacitor array structure have been widely used because of its simple architecture and relatively high speed.However,conventional SAR ADCs consume relatively high energy due to the large number of capacitors used in the capacitor array and their sizes scaled up along with the number of bits.The proposed architecture reduces the energy consumption as well as the capacitor size by employing a new array architecture that scales down the reference voltages instead of scaling up the capacitor sizes.The proposed 12-bit SAR ADC is implemented in Complementary Metal Oxide Semiconductor(CMOS)0.13 um library using Cadence Virtuoso design tool.Simulation results and mathematical model demonstrate the overall energy savings of up to 97.3%compared with conventional SAR ADC,67%compared with the SAR ADC with split capacitor,and 35%compared with the resistor and capacitor(R&C)Hybrid SAR ADC.The ADC achieves an effective number of bits(ENOB)of 11.27 bits and consumes 61.7 uW at sampling rate of 2.56 MS/s,offering an energy consumption of 9.8 fJ per conversion step.The proposed SAR ADC offers 95.5%reduction in chip core area compared to conventional architecture,while occupying an active area of 0.088 mm2.
基金This work has been supported by the Science and Technology Research Project of Chongqing Education Commission,China(No.KJ1704076)the Project of Chongqing University of Posts and Telecommunications,China(No.A2016-106)the Basic and Advanced Technology Research Project of Chongqing Municipality,China(No.cstc2018jcyjAX0560).
文摘In this paper,we report the design and simulation of a bias-selectable dual-band photodetector operating in the visible(VIS)and near infrared(NIR)regions.The photodetector consists of two back-to-back avalanche photodiodes(APDs)with InGaAs and Si absorption layers respectively.The structure and electrical and optical properties of the dual-color photodetector were designed and simulated by exploiting Silvaco software.The results obtained on the basis of numerical simulation include the current-voltage,capacitance-voltage,spectral response,etc.The optical simulation shows the detection capability in the VIS and NIR ranges,cut-off wavelengths of 1.0μm and 1.8μm depending on the applied bias polarity.Comparing with using the PIN structure as element device,the dual-band photodetector based on the APD configuration could detect the very weak signal,realizing few photons,even single photon detection.
基金the National Natural Science Foundation of China under Grant 52007071 and 51907073the China Postdoctoral Science Foundation under Grant 3004131154 and 2020M672355the Applied Basic Frontier Program of Wuhan under Grant 2020010601012207。
文摘To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.
基金National Research Foundation (NRF) of South Korea (NRF-2022R1A2C1004392)Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (IRIS RS-202300240109)。
文摘Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles(mNPs) on the surfaces of catalytic metal oxide supports is challenging.This can be attributed to the heterogeneity and large size at the nanoscale,the poorly defined catalyst nanostructure,and thermodynamic immiscibility of the strongly repelling metallic elements.To address these challenges,an ultrasonic-assisted coincident electro-oxidation-reduction-precipitation(U-SEO-P) is presented to fabricate ultra-stable PtRuAgCoCuP NPs,which produces numerous active intermediates and induces strong metal-support interactions.To sort the active high-entropy mNPs,individual NPs are described on the support surface and the role of deep learning in understanding/predicting the features of PtRuAgCoCu@TiO_(x) catalysts is explained.Notably,this deep learning approach required minimal to no human input.The as-prepared PtRuAgCoCu@TiO_(x) catalysts can be used to catalyze various important chemical reactions,such as a high reduction conversion(100% in 30 s),with no loss of catalytic activity even after 20 cycles of nitroarene and ketone/aldehyde,which is several times higher than commercial Pt@TiO_(x) owing to individual PtRuAgCoCuP NPs on TiO_(x) surface.In this study,we present the "Totally Defined Catalysis" concept,which has enormous potential for the advancement of high-activity catalysts in the reduction of organic compounds.
基金National Natural Science Foundation of China under Grant No.10647133the Research Foundation of the Education Department of Jiangxi Province under Grant No.[2007]22
文摘A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（θ;μ;κ） is a two-mode rotational displacing-squeezing operator in the 〈η｜ representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac＇s representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.
